Security firm that employed Mateen was contractor for the Department of Homeland Security

G4S, the employer of the Muslim terrorist who killed 49 people at the Orlando Pulse nightclub, is a major contractor for the Department of Homeland Security and State Department.

Daniel Gilroy, who worked with Mateen at G4S, said he made repeated formal complaints about Mateen’s aggressive behavior and alleged family connections to Al Qaida, but eventually quit his job when G4S refused to fire Mateen.

“Omar Mateen was employed by G4S at a residential community in South Florida,” the company said in a statement, adding Mateen “was subject to detailed company screening when he was recruited in 2007 and re-screened in 2013 with no adverse findings.”

“He was also subject to checks by a U.S. law enforcement agency with no findings reported to G4S.”

G4S, based in the UK, employs more than 610,000 people around the world, according to its website. The company oversees security at 40 U.S. embassies worldwide and also assists U.S. Border Patrol agents.

Gilroy, a former Fort Pierce police officer, told Florida Today he had raised concerns with his G4S supervisors after Mateen talked about killing people. Gilroy said his complaints were ignored by his superiors because Mateen was Muslim.

“I quit because everything he said was toxic and the company wouldn’t do anything. This guy was unhinged and unstable. He talked of killing people,” said Gilroy.

Other G4S employees eventually joined in and notified federal agents of Mateen’s comments. Mateen admitted to having made the remarks when questioned by the FBI, which later removed him from the federal watch list.